This front system features the S4 4-piston caliper mounted to a 11 inch 2-piece slot, drill, zinc plated rotor. Baer systems include calipers that have D.O.T. compliant dust and weather seals. Quality bearings used, along with NAS high grade stainless hardware for our pre-assembled 2-piece rotor. The SS4+ is designed just like Baers larger systems, but in a smaller package for 15 inch wheels.Fitment: